This investigation is designed to improve the therapeutic ratio in radiation therapy of neoplastic disease by the use of topical chemical radioprotectors. Specific objectives include: 1) to study the development of radiation ophthalmopathy in the eye of the rabbit after typical radiation therapy treatment; 2) to study the effects of varying concentrations of dimethyl sulfoxide (DMSO) with and without radiation treatment on eye pathology; 3) to test the effects of topical S-2-(3- aminopropylamino) ethylphorothioate (WR 2721) with and without DMSO and radiation treatment on the eye; 4) to test the cellular kinetic response of the cornea and lens epithelium after DMSO alone, DMSO, plus WR 2721, DMSO plus radiation treatment, WR 2721 plus radiation treatment, and SMSO plus WR 2721 plus radiation treatment, and 5) to determine if there exists in this system a differential effect between normal and malignant tissue. It is expected that this investigation will provide qualitative and quantitative data on the effects of increasing the resistance of normal structures while leaving the tumor resistance unchanged. It is hoped that this initial study will yield sufficient data to warrant clinical trials in hopes of increasing the therapeutic ratio in the radiation treatment of cancer.